（12）muduo_base库源码分析：Exception类实现

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1.Exception类实现

• 类图
  
• 12\jmuduo\muduo\base\Exception.cc

// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)#include <muduo/base/Exception.h>#include <cxxabi.h>//demangle需要的头文件
#include <execinfo.h>
#include <stdlib.h>
#include <stdio.h>//demangle需要的头文件using namespace muduo;Exception::Exception(const char* msg): message_(msg)
{fillStackTrace();
}Exception::Exception(const string& msg): message_(msg)
{fillStackTrace();
}Exception::~Exception() throw ()
{
}const char* Exception::what() const throw()
{return message_.c_str();
}const char* Exception::stackTrace() const throw()
{return stack_.c_str();
}//构造函数中，已经将栈回溯信息给填充了，下面照抄man backtrace的eg
//登记栈回溯信息，保存在变量stack_中
void Exception::fillStackTrace()
{const int len = 200;void* buffer[len];//指针数组//backtrace:栈回溯，保存各个栈帧的地址int nptrs = ::backtrace(buffer, len);//将栈帧的函数地址保存在指针buffer所指向的数组中//backtrace_symbols，根据地址，转成相应的函数符号char** strings = ::backtrace_symbols(buffer, nptrs);//将地址转换成函数名称if (strings){for (int i = 0; i < nptrs; ++i){// TODO demangle funcion name with abi::__cxa_demangle用于将函数名字还原//stack_.append(strings[i]);//C++的函数名字，会做名字改编，改编成如下图所示stack_.append(demangle(strings[i]));//名字不改编的写法stack_.push_back('\n');}free(strings);}
}
//demangle名字不改编的实现
string Exception::demangle(const char* symbol)
{size_t size;int status;char temp[128];char* demangled;//first, try to demangle a c++ nameif (1 == sscanf(symbol, "%*[^(]%*[^_]%127[^)+]", temp)) {if (NULL != (demangled = abi::__cxa_demangle(temp, NULL, &size, &status))) {string result(demangled);free(demangled);return result;}}//if that didn't work, try to get a regular c symbolif (1 == sscanf(symbol, "%127s", temp)) {return temp;}//if all else fails, just return the symbolreturn symbol;
}

• 12\jmuduo\muduo\base\Exception.h

// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)#ifndef MUDUO_BASE_EXCEPTION_H
#define MUDUO_BASE_EXCEPTION_H#include <muduo/base/Types.h>
#include <exception>namespace muduo
{class Exception : public std::exception
{public:explicit Exception(const char* what);explicit Exception(const string& what);virtual ~Exception() throw();virtual const char* what() const throw();const char* stackTrace() const throw();private:void fillStackTrace();string demangle(const char* symbol);//名字不改编的写法，新增string message_;string stack_;
};}#endif  // MUDUO_BASE_EXCEPTION_H

2.测试

• 12\jmuduo\muduo\base\tests\Exception_test.cc

#include <muduo/base/Exception.h>
#include <stdio.h>class Bar
{public:void test(){throw muduo::Exception("oops");//调用构造函数抛出异常}
};void foo()
{Bar b;b.test();
}int main()
{try{foo();}catch (const muduo::Exception& ex){printf("reason: %s\n", ex.what());printf("stack trace: %s\n", ex.stackTrace());//ex.stackTrace返回栈回溯的信息}
}

• 12\jmuduo\muduo\base\tests\CMakeLists.txt

add_executable(atomic_unittest Atomic_unittest.cc)
#target_link_libraries(atomic_unittest muduo_base)##新增
add_executable(exception_test Exception_test.cc)
target_link_libraries(exception_test muduo_base)## 需要链接muduo_baseadd_executable(timestamp_unittest Timestamp_unittest.cc)
target_link_libraries(timestamp_unittest muduo_base)

• 12\jmuduo\muduo\base\CMakeLists.txt

set(base_SRCSException.cc ##新增 Timestamp.cc)。。。。。。

• 结果如下：
  

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